It’s taken almost two decades, but the U.S. Food and Drug Administration may be close to a ruling on the world’s first genetically modified animal protein.

AquAdvantage salmon is a product of the Massachusetts-based biotech firm AquaBounty Technologies. Designed to reach market size in about half the time of standard farmed salmon, the fish would be the first genetically engineered animal approved for human consumption. Producers say the salmon is safe to eat, environmentally friendly and can feed more of the population with less resources, compared to other farmed fish.

But last week two major store chains, Kroger and Safeway, joined a growing list of supermarkets that say that they will refuse to sell the salmon -- dubbed “frankenfish” by critics -- raising questions about whether consumers will buy it, even with the FDA’s approval.

The issue is highly controversial. Environmentalists, consumer watchdogs, select supermarket chains, Alaskan fishermen and various other groups have been voicing strong opposition to the potentially game-changing product since AquaBounty applied for approval in 1996.

“Before we say we’ve come up with a way to feed the growing population, what are we putting at risk in exchange?” says Dana Perls, a policy campaigner at the environmental organization Friends of the Earth. “We really need to know what we’re doing. We want to make sure we’re taking the right steps in the long run as opposed to wishing we’d done something later.”

“I think consumers, once they have a chance to see these products and touch them and taste them, will say, ‘Gee, what was all the fuss about?’”

- AquaBounty CEO Ron Stotish

The technology to build a better salmon has been around since 1989. Essentially, AquaBounty took an Atlantic salmon and added a growth gene from the Chinook salmon and a promoter gene from the ocean pout (an eel-like species) to create AquAdvantage.

“This is a new way of growing salmon,” he says. “It’s land-based; it reduces the cost of transportation. Ninety-one percent of seafood we consume is imported. With this product we could grow these fish here in the U.S.”

Based on the FDA’s preliminary finding that an approval of AquaBounty’s application “would not have a significant impact (FONSI) on the U.S. environment,” many believe an approval is pending. But even if approved, it may take some time before GMO (genetically modified organism) salmon is available in stores, due to the growth of the fish and other commercial issues, Stotish says.

While the FDA has remained mum on the subject, environmental groups have been ramping up lobbying efforts to keep stores from stocking it if it is approved. More than 60 retailers have stated they won’t carry the product, totaling more than 9,000 stores nationwide.

“Public perception is not necessarily negative, but suspicious,” says Jon Entine, the author and founder of the Genetic Literacy Project who wrote an investigative piece for Slate in 2012 arguing that the science behind AquAdvantage is sound, and that the extended FDA delays are political maneuvers.

He believes AquaBounty will eventually overcome the naysayers.

In 2010 the FDA stated in a Veterinary Medicine Advisory Committee briefing that AquAdvantage salmon was indistinguishable from standard Atlantic salmon. “We have found no biologically relevant difference between food from ABT salmon and conventional Atlantic salmon based on the criteria evaluated,” it wrote.

And, according to Stotish, the GMO salmon tastes just as good. He testified in a 2010 FDA hearing that AquAdvantage won out over Canadian and Chilean salmon varieties in blind taste tests.

“I think consumers, once they have a chance to see these products and touch them and taste them, will say, ‘Gee, what was all the fuss about?’” Stotish says.

But groups like Friends of the Earth and the Center for Food Safety say consumers don’t want the product and have called the FDA’s initial scientific assessment flawed and incomplete. Opponents argue that, although they have been designed to be all female and sterile, the fish have the potential to escape containment, breed and decimate wild populations. (AquaBounty says its data debunks these claims.)

According to the CFS, during the FDA’s public comment period last year, 1.8 million people sent messages to the FDA opposing the approval of AquAdvantage.

“At the level of response that we’re seeing from grocery stores and consumers, I don’t think there is enough demand for this genetically modified salmon to make it onto the market. There’s no room for it on the market. Nine thousand stores have already said, ‘We’re not going to sell this,’” Perls says.

Already on the anti-GMO salmon bandwagon are Whole Foods, Trader Joe’s, Safeway, Kroger and Target, among others. But other chains remain silent. Wal-mart, for example, said it had “nothing to add at this time” when contacted for comment.

“There is the potential for a total rejection of GMO salmon and also for broad acceptance,” says business research analyst Howard Waxman, who wrote a 2013 report for MarketResearch.com on non-GMO foods that addressed the growing market and labeling trends. “There will be a public relations war if the FDA gives approval.”

The FDA has said it likely will not require that GMO fish be labeled, so if retailers carry it, consumers may not know the difference.

“Consumers want to know what they’re eating and what the impact of what they’re eating has on their bodies and the environment and their families and children,” Perls says.

“This is a marathon, not a sprint,” Entine says. “Ten years from now the educated public is going to look back with a great sense of embarrassment at how fiercely groups that call themselves 'progressive' whipped up emotional concerns about whether GMOs are safe or sustainable. This opposition is based on ideology trumping science, at least in the short term.”

Perls disagrees, and thinks consumer demand will drive market behavior – straight to the rejection of genetically modified fish and other meats.

But Stotish thinks the market will bear out the opposite result.

“American free enterprise has always worked well and it will continue to work well,” he says. “If you have a good product, you will be successful.”